[ikalugin]

First of all - nuclear weapons make the scenario impossible. Germany could not rapidly nuclearise due to the lack of relevant industries. If it does it could not nuclearise at the same rate as Russia does.
Should the strategic nuclear balance be skewed the way it is now (between Russia and Germany or Germany and the France+UK for that matter) the response to the mass invasion and/or existential threat (because German invasion of USSR during WW2 was an existential threat to Soviet people) then it would be rational to immidietely employ tactical and then strategic weapons in mass. This is what the nuclear weapons are there for - deterence.

Secondly - modern Armed Forces precludes large formations due to the costs (especially manpower). This means that deep, sustained land operations would occur in the environment without a front, with open strategic and most likely operational level flanks, in a largerly hostile area with hostile and well armed population.

There are reasons why WW2 (or WW1) would not repeat itself.